The present invention is related generally to the field of workpiece processing such as, for example, processing semiconductor wafers and, more particularly, to a multi-workpiece processing chamber and its method of use.
A number of processing systems, currently used in the production of semiconductor wafers, are capable of processing more than one wafer at a time for purposes of enhancing system throughput. It has been asserted in the prior art, however, that a single-wafer process chamber provides more uniform process results when compared to multi-wafer processing chamber configurations. Presumably, this degradation in “across-wafer” and “station-to-station” uniformity is thought to be directly attributable to communication between adjacent wafer processing stations within a shared process chamber and environment.
Process uniformity, however, is of increasing concern, particularly in view of an industry emphasis on ever-decreasing device feature sizes. One example, attempting to provide a compromise between the asserted “cross-talk” contamination problem that is associated with batch processing in a shared process environment and limited throughput in the use of single-wafer process chamber, is seen in U.S. Pat. No. 5,855,681 (hereinafter the '681 patent). The latter adopts the use of “tandem” single wafer processing chambers, having processing regions that are described as being separate from one another (see col. 4, ln. 37-40). A single chamber body is used to define these separate processing regions using a shared chamber wall between the processing stations. The processing region defined by each tandem chamber is deemed by the patent as isolatable from the processing region of the other tandem chamber by virtue of limiting communication between the adjacent processing regions only to that which selectively occurs through an exhaust system. Such selective communication would presumably be controlled based on the pumping status of the vacuum pumping system. Otherwise, the tandem chambers appear to function, from a process standpoint, in a way which is essentially the same as a pair of separate single-wafer processing chambers (see, for example, col. 2, lns. 54-56). In this regard, the system provides for multiple, isolated processes to be performed concurrently in at least two regions (see col. 4, ln. 44-51), which reasonably suggests that a first process can be performed in one processing region of a tandem chamber while a second, different process is performed in the other processing region of that same tandem chamber.
While there may be advantages associated with the asserted capabilities of the separate, tandem chambers of the '681 patent in providing for simultaneously executing different processes in each chamber, it is recognized herein that there is a concern that, even if the same process is executed in both chambers, the chambers may provide different results as the conditions in each chamber are too independent and there is no feedback control that would keep these conditions equal. For example, this could occur if there is any tendency for contaminants to build up in exhaust channels 621, leading to different pressures in one chamber with respect to the other. In view of the foregoing and whereas the overall complexity of the '681 chamber design was intended to improve the cross-talk problem, resulting in a high cost of the chamber, it is believed that further improvement is needed.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.